Cell Handover Method And Terminal Device

ABSTRACT

A terminal device may determine that the terminal device camps on a first cell and is located within a coverage area of a second cell. The terminal device determines that no data service has been received within a preset-duration. The terminal device further determines that a radio resource control (RRC) connection is not released when no data service is received within the preset duration. The terminal device performs a hand over from the first cell to the second cell upon determining that the RRC connection is not released.

TECHNICAL FIELD

Embodiments of the present invention relate to communicationstechnologies, and in particular, to a cell handover method and aterminal device.

BACKGROUND

Currently, with continuous development of communications technologies, a4G communications network based on a Long Term Evolution (Long TermEvolution, LTE for short) technology emerges. The 4G communicationsnetwork has advantages such as a fast network speed, good communicationquality, and always in service, and brings good experience to a user.

However, in a process in which the user uses a terminal device in the 4Gcommunications network, if a configuration of a cell in which theterminal device is located is abnormal, power consumption of theterminal device increases, and consequently a battery life of theterminal device is relatively short and cannot meet a requirement of theuser in actual use.

SUMMARY

Embodiments of the present invention provide a cell handover method anda terminal device, to resolve a prior-art technical problem that powerconsumption of the terminal device increases and a battery life of theterminal device is relatively short because a configuration of a cell inwhich the terminal device is located is abnormal.

A first aspect of the embodiments of the present invention provides acell handover method. A terminal device currently camps on a first cell,the terminal device is further currently located in a coverage area of asecond cell, and the method includes: when determining that no dataservice is transmitted within preset duration, determining, by theterminal device, whether a radio resource control RRC connection isreleased; and when determining that the RRC connection is not released,handing over, by the terminal device, from the first cell to the secondcell.

According to the cell handover method provided in the first aspect, whenno data service is transmitted within the preset duration, the terminaldevice that camps on the first cell may determine whether the RRCconnection to a base station to which the first cell belongs isreleased. Further, when determining that the RRC connection is notreleased, the terminal device may determine that a configuration of thefirst cell is abnormal, and hand over from the first cell with theabnormal configuration to the second cell. This avoids a problem thatpower consumption of the terminal device increases because the terminaldevice maintains the RRC connection to the base station of the firstcell, reduces the power consumption of the terminal device, and prolongsa battery life of the terminal device.

Optionally, the handing over, by the terminal device, from the firstcell to the second cell includes: determining, by the terminal device,whether the terminal device is currently in a screen-off state; and whenthe terminal device is currently in a screen-off state, handing over, bythe terminal device, from the first cell to the second cell.

According to the cell handover method provided in this possibleimplementation, when the terminal device is currently in a screen-offstate, the terminal device may directly hand over from the first cellwith the abnormal configuration to the second cell. This reduces thepower consumption of the terminal device while ensuring user experience.

For example, the handing over, by the terminal device, from the firstcell to the second cell includes: handing over, by the terminal device,from the first cell to the second cell, and recording an identifier ofthe first cell.

According to the cell handover method provided in this possibleimplementation, when completing a cell handover procedure, the terminaldevice may further record the identifier of the first cell, so that whenthe terminal device moves to coverage areas of the first cell and thesecond cell again, the terminal device can determine, by using therecorded identifier of the first cell, that the configuration of thefirst cell is abnormal, to avoid accessing the first cell, and preventthe first cell with the abnormal configuration from affecting the powerconsumption of the terminal device. This further reduces the powerconsumption of the terminal device, and further prolongs the batterylife of the terminal device.

Optionally, the handing over, by the terminal device, from the firstcell to the second cell includes:

-   -   determining, by the terminal device, whether the terminal device        is currently in a screen-off state;    -   when the terminal device is currently in a screen-on state,        recording, by the terminal device, an identifier of the first        cell;    -   when the terminal device enters a screen-off state from a        screen-on state, determining, by the terminal device, whether an        identifier of a cell on which the terminal device currently        camps is the recorded identifier of the first cell; and    -   when the identifier of the cell on which the terminal device        currently camps is the recorded identifier of the first cell,        handing over, by the terminal device, from the first cell to the        second cell.

According to the cell handover method provided in this possibleimplementation, when the terminal device is currently in a screen-onstate, the terminal device may first record the identifier of the firstcell. After the terminal device enters a screen-off state, the terminaldevice determines whether the identifier of the cell on which theterminal device currently camps is the same as the recorded identifierof the first cell, and when the identifier of the cell on which theterminal device currently camps is the same as the recorded identifierof the first cell, the terminal device performs the cell handoverprocedure, to hand over from the first cell with the abnormalconfiguration to the second cell. This avoids bringing unstable networkexperience to a user, and reduces the power consumption of the terminaldevice while ensuring user experience.

For example, the first cell and the second cell are cells in anintra-RAT communications network.

For example, the first cell and the second cell are cells in inter-RATcommunications networks.

A second aspect of the embodiments of the present invention provides aterminal device. The terminal device currently camps on a first cell,the terminal device is further currently located in a coverage area of asecond cell, and the terminal device includes: a determining module,configured to: when determining that no data service is transmittedwithin preset duration, determine whether a radio resource control RRCconnection is released; and a handover module, configured to: when it isdetermined that the RRC connection is not released, hand over theterminal device from the first cell to the second cell.

Optionally, the handover module includes: a first determining unit,configured to determine whether the terminal device is currently in ascreen-off state; and a first handover unit, specifically configured to:when the terminal device is currently in a screen-off state, hand overthe terminal device from the first cell to the second cell.

For example, the first handover unit is specifically configured to: handover the terminal device from the first cell to the second cell, andrecord an identifier of the first cell.

Optionally, the handover module includes: a second determining unit,configured to determine whether the terminal device is currently in ascreen-off state; a recording unit, configured to: when the terminaldevice is currently in a screen-on state, record an identifier of thefirst cell; a third determining unit, configured to: when the terminaldevice enters a screen-off state from a screen-on state, determinewhether an identifier of a cell on which the terminal device currentlycamps is the recorded identifier of the first cell; and a secondhandover unit, configured to: when the identifier of the cell on whichthe terminal device currently camps is the recorded identifier of thefirst cell, hand over the terminal device from the first cell to thesecond cell.

For example, the first cell and the second cell are cells in anintra-RAT communications network.

For example, the first cell and the second cell are cells in inter-RATcommunications networks. For beneficial effects of the terminal deviceprovided in the second aspect and the possible implementations of thesecond aspect, refer to the beneficial effects brought by the firstaspect and the possible implementations of the first aspect. Details arenot described herein again.

A third aspect of the embodiments of the present invention provides aterminal device. The terminal device currently camps on a first cell,the terminal device is further currently located in a coverage area of asecond cell, and the terminal device includes a processor and a memory.The memory is configured to store computer-executable program code, andthe program code includes an instruction; and when the processorexecutes the instruction, the instruction enables the terminal device toperform the cell handover method in the first aspect and the possibleimplementations of the first aspect. For beneficial effects of the thirdaspect, refer to the beneficial effects brought by the first aspect andthe possible implementations of the first aspect. Details are notdescribed herein again.

A fourth aspect of the embodiments of the present invention provides aterminal device, including at least one processing element (or chip) forperforming the method in the first aspect.

A fifth aspect of the embodiments of the present invention provides aprogram. The program is used to perform the method in the first aspectwhen being executed by a processor.

A sixth aspect of the embodiments of the present invention provides aprogram product, for example, a computer-readable storage medium,including the program in the fifth aspect.

According to the cell handover method and the terminal device providedin the embodiments of the present invention, when no data service istransmitted within the preset duration, the terminal device that campson the first cell may determine whether the RRC connection to the basestation to which the first cell belongs is released. Further, whendetermining that the RRC connection is not released, the terminal devicemay determine that the configuration of the first cell is abnormal, andhand over from the first cell with the abnormal configuration to thesecond cell. This avoids a problem that the power consumption of theterminal device increases because the terminal device maintains the RRCconnection to the base station of the first cell, reduces the powerconsumption of the terminal device, and prolongs the battery life of theterminal device.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic flowchart of a cell handover method according toan embodiment of the present invention;

FIG. 2A and FIG. 2B are a schematic flowchart of another cell handovermethod according to an embodiment of the present invention;

FIG. 3 is a schematic diagram 1 of power consumption of a terminaldevice according to an embodiment of the present invention;

FIG. 4 is a schematic diagram 2 of power consumption of a terminaldevice according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a terminal device accordingto an embodiment of the present invention;

FIG. 6 is a schematic structural diagram of another terminal deviceaccording to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of still another terminaldevice according to an embodiment of the present invention;

FIG. 8 is a schematic structural diagram of still another terminaldevice according to an embodiment of the present invention; and

FIG. 9 is a block diagram of a partial structure when a terminal deviceis a mobile phone according to an embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

A terminal device in the embodiments of the present invention may be adevice that provides a user with voice and/or data connectivity, ahandheld device with a radio connection function, or another processingdevice connected to a wireless modem. A wireless terminal maycommunicate with one or more core networks by using a radio accessnetwork (Radio Access Network, RAN). The wireless terminal may be amobile terminal such as a mobile phone (also referred to as a “cellular”phone) and a computer with a mobile terminal, for example, may be aportable, pocket-sized, handheld, computer built-in, or in-vehiclemobile apparatus, which exchanges language and/or data with the radioaccess network. For example, the wireless terminal may be a device suchas a personal communication service (PCS, Personal CommunicationService) phone, a cordless telephone set, a Session Initiation Protocol(SIP) phone, a wireless local loop (WLL, Wireless Local Loop) station,or a personal digital assistant (PDA, Personal Digital Assistant). Thewireless terminal may also be referred to as a system, a subscriber unit(Subscriber Unit), a subscriber station (Subscriber Station), a mobilestation (Mobile Station), a mobile console (Mobile), a remote station(Remote Station), an access point (Access Point), a remote terminal(Remote Terminal), an access terminal (Access Terminal), a user terminal(User Terminal), a user agent (User Agent), a user device (User Device),or user equipment (User Equipment).

In the prior art, when a user uses a terminal device in a 4Gcommunications network, the terminal device may perform datatransmission with a base station by using a radio resource control(Radio Resource Control, RRC for short) connection that is establishedto the base station to which a cell belongs. After the user stops usingthe terminal device, no data is transmitted between the terminal deviceand the base station. Therefore, the base station may send an RRCconnection release request to the terminal device, so that the terminaldevice can release the RRC connection, to avoid increasing powerconsumption of the terminal device because the terminal device maintainsthe RRC connection to the base station.

In this case, if a configuration of a cell in which the terminal deviceis located is abnormal, for example, a parameter related to an RRCdisconnection time in a configuration parameter of the cell is abnormal,after the user stops using the terminal device, the base station towhich the cell belongs does not send the RRC connection release requestto the terminal device, so that when no data is transmitted between thebase station and the terminal device, the RRC connection is stillmaintained between the base station and the terminal device. Theterminal device maintains the RRC connection to the base station byusing a modem of the terminal device. To be specific, when no data istransmitted between the base station and the terminal device, the RRCconnection is still maintained between the modem of the terminal deviceand the base station, and therefore the modem needs to continuouslywork. This increases the power consumption of the terminal device, andshortens a battery life of the terminal device.

In view of the foregoing case, the embodiments of the present inventionprovide a cell handover method, so that if the terminal device cannotrelease the RRC connection after no data is transmitted, the terminaldevice can hand over to another cell with a normal configuration, toavoid a case in which when no data is transmitted between the terminaldevice and the base station, the RRC connection is still maintainedbetween the terminal device and the base station. This can furtherreduce the power consumption of the terminal device, and prolong thebattery life of the terminal device. Therefore, the cell handover methodprovided in the embodiments of the present invention aims to resolve aprior-art technical problem that the power consumption of the terminaldevice increases and the battery life is relatively short because theconfiguration of the cell in which the terminal device is located isabnormal.

It should be noted that the cell handover method provided in theembodiments of the present invention includes but is not limited to theapplication scenario of the terminal device in the 4G communicationsnetwork. A person skilled in the art may understand that the cellhandover method provided in the embodiments of the present invention maybe used in all scenarios in which the power consumption of the terminaldevice increases because the configuration of the cell on which theterminal device camps is abnormal. The following application document isdescribed by using the 4G communications network as an example.

The following describes technical solutions in this application indetail with reference to specific embodiments. The following specificembodiments may be mutually combined, and same or similar concepts orprocesses may not be repeatedly described in some embodiments.

FIG. 1 is a schematic flowchart of a cell handover method according toan embodiment of the present invention. In this embodiment, a terminaldevice currently camps on a first cell and is located in a coverage areaof one or more second cells. To be specific, the terminal device maytransmit a data service by establishing an RRC connection to a basestation to which the first cell belongs. This embodiment includes aspecific process in which when determining that the RRC connection isnot released, the terminal device hands over from the first cell to asecond cell. As shown in FIG. 1, the method may include the followingsteps:

S101. When determining that no data service is transmitted within presetduration, the terminal device determines whether the RRC connection isreleased.

S102. When determining that the RRC connection is not released, theterminal device hands over from the first cell to the second cell.

Specifically, the preset duration may be specifically determined basedon a manner in which a base station to which a cell with a normalconfiguration belongs sends an RRC connection release request. Forexample, if no data service is transmitted between the base station towhich the cell with the normal configuration belongs and the terminaldevice within 10 seconds, the base station sends the RRC connectionrelease request to the terminal device, and the preset duration may begreater than or equal to 10 seconds, If no data service is transmittedbetween the base station to which the cell with the normal configurationbelongs and the terminal device within one minute, the base stationsends the RRC connection release request to the terminal device, and thepreset duration may be greater than or equal to one minute.

In this case, after a user stops using the terminal device, the terminaldevice may determine, based on whether data sent by the base station towhich the first cell belongs is received within the preset duration andwhether data is sent within the preset duration to the base station towhich the first cell belongs, whether a data service is transmittedwithin the preset duration. If the terminal device does not receive,within the preset duration, the data sent by the base station to whichthe first cell belongs, and does not send, within the preset duration,the data to the base station to Which the first cell belongs, theterminal device may determine that no data service is transmitted withinthe preset duration. Then, the terminal device may further determine,based on Whether the terminal device receives, within the presetduration, the RRC connection release request sent by the base station towhich the first cell belongs, whether the RRC connection between theterminal device and the base station to which the first cell belongs isreleased.

When the RRC connection release request sent by the base station towhich the first cell belongs is received within the preset duration, itindicates that an RRC connection release procedure is normally performedbetween the terminal device and the base station to which the first cellbelongs, in other words, the configuration of the first cell is normal.Therefore, the terminal device may determine that the RRC connectionbetween the terminal device and the base station to which the first cellbelongs is released. In this case, the terminal device does notencounter a case in which “when no data is transmitted between theterminal device and the base station to which the first cell belongs,the RRC connection is still maintained between the terminal device andthe base station to which the first cell belongs”, and further, powerconsumption of the terminal device does not increase due to this case.Therefore, in this case, the terminal device may continue to camp on thefirst cell and does not take any measure.

When the RRC connection release request sent by the base station towhich the first cell belongs is not received within the preset duration,it indicates that the configuration of the first cell is abnormal, andthe RRC connection release procedure is not performed within the presetduration between the terminal device and the base station to which thefirst cell belongs. Therefore, the terminal device may determine thatthe RRC connection between the terminal device and the base station towhich the first cell belongs is not released. In this case, no data istransmitted between the terminal device and the base station to whichthe first cell belongs. However, the RRC connection is still maintainedbetween the terminal device and the base station to which the first cellbelongs. To be specific, the RRC connection is still maintained betweena modem of the terminal device and the base station to which the firstcell belongs, and therefore the modem of the terminal needs tocontinuously work. This increases the power consumption of the terminaldevice, and shortens a battery life of the terminal device, In thiscase, the terminal device may hand over from the first cell with theabnormal configuration to the second cell. If the second cell is a cellwith a normal configuration, after the terminal device hands over to thesecond cell, when no data is transmitted between the terminal device anda base station to which the second cell belongs, an RRC connection maybe normally released between the terminal device and the base station towhich the second cell belongs, to avoid increasing the power consumptionof the terminal device and further prolong the battery life the terminaldevice.

An implementation in which the terminal device hands over from the firstcell to the second cell is not limited in this embodiment. Optionally,if the second cell is also a cell in a 4G communications network, thefirst cell and the second cell are cells in an intra-RAT communicationsnetwork. When determining that the RRC connection is not released, theterminal device may send a pseudo measurement report generated by theterminal device to the base station to which the first cell belongs. Thepseudo measurement report is used to indicate to the base station towhich the first cell belongs that a channel condition is relatively poorwhen the terminal device currently camps on the first cell. In this way,after receiving the measurement report, the base station to which thefirst cell belongs may determine, based on the measurement report, thatthe terminal device currently meets a cell handover condition, andinstruct, by sending a cell handover instruction to the terminal device,the terminal device to hand over from the first cell to the second cell,so that the terminal device can hand over from the first cell to thesecond cell according to the cell handover instruction. In this case, ifthe terminal device is currently located in the coverage area of the oneor more second cells, the base station may select a suitable second cellfor the terminal device by performing an existing cell handoverprocedure, and instruct the terminal device to hand over from the firstcell to the second cell.

Optionally, if the second cell is a cell in a communications networkcorresponding to a communications standard earlier than a communicationsstandard corresponding to the 4G communications network, for example, a3G communications network, or a 2G communications network, the firstcell and the second cell are cells in inter-RAT communications networks.The 3G communications network is used as an example. When determiningthat the RRC connection is not released, the terminal device may furthersend, to the base station to which the first cell belongs, a networkcapability change request indicating that the terminal device does notsupport the 4G communications network, so that a communications systemin which the 4G communications network is located and a communicationssystem in which the 3G communications network is located can allow theterminal device to re-search for the 3G communications network and campon the second cell in the 3G communications network, and the terminaldevice hands over from the first cell to the second cell.

According to the cell handover method provided in this embodiment of thepresent invention, when no data service is transmitted within the presetduration, the terminal device that camps on the first cell may determinewhether the RRC connection to the base station to which the first cellbelongs is released. Further, when determining that the RRC connectionis not released, the terminal device may determine that theconfiguration of the first cell is abnormal, and hand over from thefirst cell with the abnormal configuration to the second cell. Thisavoids a problem that the power consumption of the terminal deviceincreases because the terminal device maintains the RRC connection tothe base station of the first cell, reduces the power consumption of theterminal device, and prolongs the battery life of the terminal device.

Further, based on the foregoing embodiment, before handing over from thefirst cell to the second cell, the terminal device may further determinewhether the terminal device is currently in a screen-off state. For howthe terminal device determines whether the terminal device is currentlyin a screen-off state, refer to the prior art.

Case 1: The terminal device is currently in a screen-off state.

Specifically, if the terminal device determines that the RRC connectionis not released, the terminal device is currently in a screen-off state,indicating that the user does not use the terminal device currently. Inthis case, if the terminal device performs a cell handover procedure,the user is not affected. Therefore, the terminal device may directlyhand over from the first cell with the abnormal configuration to thesecond cell. This reduces the power consumption of the terminal devicewhile ensuring user experience.

Further, when completing the cell handover procedure, the terminaldevice may further record an identifier of the first cell, so that whenthe terminal device moves to coverage areas of the first cell and thesecond cell again, the terminal device may determine, by using therecorded identifier of the first cell, that the configuration of thefirst cell is abnormal, to avoid accessing the first cell, and preventthe first cell with the abnormal configuration from affecting the powerconsumption of the terminal device. This further reduces the powerconsumption of the terminal device, and further prolongs the batterylife of the terminal device. Optionally, in another implementation ofthis embodiment of the present invention, the identifier of the firstcell recorded by the terminal device may correspond to preset duration.After accumulated duration of recording the identifier of the first cellreaches the preset duration, the terminal device may delete theidentifier of the first cell, to lift a restriction that the terminaldevice cannot camp on the first cell. In this manner, after theconfiguration of the first cell is restored to normal, the terminaldevice may still access the first cell after moving to the first cell,to ensure normal communication of the terminal device. The presetduration may be specifically determined based on a restoration time ofthe first cell with the abnormal configuration.

Case 2: The terminal device is currently in a screen-on state.

Specifically, if the terminal device determines that the RRC connectionis not released, the terminal device is currently in a screen-on state,indicating that the user currently still uses the terminal device. Inthis case, if the terminal device performs the cell handover procedure,unstable network experience is brought to the user. Therefore, when theterminal device is currently in a screen-on state, the terminal devicemay first record the identifier of the first cell, and after theterminal device enters a screen-off state from a screen-on state,compare an identifier of a cell on which the terminal device currentlycamps with the recorded identifier of the first cell, to determinewhether the identifier of the cell on Which the terminal devicecurrently camps is the recorded identifier of the first cell. Theidentifier of the first cell described herein may be any identifier thatcan uniquely identify the first cell, for example, an ID of the firstcell.

When the identifier of the cell on which the terminal device currentlycamps is the same as the recorded identifier of the first cell, itindicates that the terminal device certainly still camps on the firstcell with the abnormal configuration. Therefore, the terminal device mayperform the cell handover procedure, to hand over from the first cellwith the abnormal configuration to the second cell. In this case, theterminal device is in a screen-off state. Therefore, the terminal deviceperforms the cell handover procedure, and unstable network experience isnot brought to the user. This reduces the power consumption of theterminal device while ensuring user experience.

When the identifier of the cell on which the terminal device currentlycamps is different from the recorded identifier of the first cell, itindicates that the terminal device certainly does not camp on the firstcell with the abnormal configuration. Therefore, the terminal device maynot perform the cell handover procedure. In this case, the terminaldevice may determine, by performing the implementation of the foregoingembodiment, whether a configuration of a current camping cell isabnormal. For an implementation and an implementation principle, referto the foregoing embodiment. Details are not described herein again.

Further, when the terminal device is currently in a screen-on state, theterminal device records the identifier of the first cell. Therefore,when the terminal device is located in the coverage areas of the firstcell and the second cell again, the terminal device may determine, byusing the recorded identifier of the first cell, that the configurationof the first cell is abnormal, to avoid accessing the first cell, andprevent the first cell with the abnormal configuration from affectingthe power consumption of the terminal device. This further reduces thepower consumption of the terminal device, and further prolongs thebattery life of the terminal device. Optionally, in anotherimplementation of this embodiment of the present invention, theidentifier of the first cell recorded by the terminal device maycorrespond to preset duration. After accumulated duration of recordingthe identifier of the first cell reaches the preset duration, theterminal device may delete the identifier of the first cell, to lift arestriction that the terminal device cannot camp on the first cell. Inthis manner, after the configuration of the first cell is restored tonormal, the terminal device may still access the first cell after movingto the first cell, to ensure normal communication of the terminaldevice. The preset duration may be specifically determined based on arestoration time of the first cell with the abnormal configuration.

According to the cell handover method provided in this embodiment of thepresent invention, when no data service is transmitted within the presetduration, the terminal device that camps on the first cell may determinewhether the RRC connection to the base station to which the first cellbelongs is released. Further, when determining that the RRC connectionis not released, the terminal device may determine that theconfiguration of the first cell is abnormal, and hand over from thefirst cell with the abnormal configuration to the second cell. Thisavoids a problem that the power consumption of the terminal deviceincreases because the terminal device maintains the RRC connection tothe base station of the first cell, reduces the power consumption of theterminal device, and prolongs the battery life of the terminal device.

The following describes in detail the cell handover method provided inthis embodiment of the present invention by using a specific example. Inthis example, a tinier may be disposed in the terminal device toimplement the foregoing preset duration, in other words, durationcorresponding to the timer is the preset duration described above. FIG.2A and FIG. 2B are a schematic flowchart of another cell handover methodaccording to an embodiment of the present invention. As shown in FIG. 2Aand FIG. 2B, the method includes the following steps.

S201. A terminal device determines whether to camp on a first cell. Ifthe terminal device determines to camp on the first cell, S202 isperformed; or if the terminal device determines not to camp on the firstcell, a procedure ends.

Specifically, the terminal device may determine, based on whether aresponse message that is used to indicate that the terminal devicesuccessfully camps and that is sent by a base station to which the firstcell belongs is received, whether the terminal device camps on the firstcell. When the terminal device receives the response message, itindicates that the terminal device camps on the first cell, and S202 isperformed. When the terminal device does not receive the responsemessage, it indicates that the terminal device does not camp on thefirst cell, and the procedure ends.

S202. The terminal device determines whether to establish an RRCconnection. If the terminal device determines to establish the RRCconnection, S203 is performed; or if the terminal device determines notto establish the RRC connection, S202 continues to be performed.

Specifically, after determining to camp on the first cell, the terminaldevice may further determine whether the RRC connection is establishedbetween the terminal device and the base station to which the first cellbelongs.

In specific implementation, the terminal device may determine, based onwhether a response message indicating that the RRC connection issuccessfully established or a response message indicating that an RRCconnection is successfully reconfigured is received, whether the RRCconnection is established between the terminal device and the basestation to which the first cell belongs. When the terminal devicereceives any one of the foregoing response messages, it indicates thatthe RRC connection is established between the terminal device and thebase station to which the first cell belongs, and S203 is performed.When the terminal device does not receive any one of the foregoingresponse messages, it indicates that the RRC connection is notestablished between the terminal device and the base station to whichthe first cell belongs, and S202 continues to be performed.

S203, The terminal device starts a timer.

Specifically, after the terminal device determines that the RRCconnection to the base station to which the first cell belongs isestablished, the terminal device may start the timer to monitor, byusing the timer, whether a configuration of the first cell is abnormal.Duration of the timer is the preset duration described in the foregoingembodiment.

S204. Before the timer expires, the terminal device determines whether adata service is transmitted. If the terminal device determines that adata service is transmitted, S203 is performed; or if the terminaldevice determines that no data service is transmitted, S205 isperformed.

Specifically, before the timer expires, the terminal device maydetermine in real time, based on whether data sent by the base stationto which the first cell belongs is received and whether data is sent tothe base station to which the first cell belongs, whether a data serviceis transmitted.

If the terminal device always has no data service to transmit before thetimer expires, when the timer expires, the terminal device may performS205. If the terminal device determines that a data service istransmitted before the timer expires, after transmission of the dataservice ends, the terminal device may go back to perform S203, so thatthe terminal device can restart the timer. Therefore, the terminaldevice can accurately determine, based on the restarted timer, whetherno data service is transmitted within the preset duration.

S205, When the timer expires, the terminal device determines whether theRRC connection is released. If the terminal device determines that theRRC connection is released, the procedure ends: or if the terminaldevice determines that the RRC connection is not released, S206 isperformed.

Specifically, if the terminal device always has no data service totransmit before the timer expires, when the tinier expires, the terminaldevice may determine, based on whether an RRC connection release requestsent by the base station to which the first cell belongs is receivedbefore the timer expires, whether the RRC connection between theterminal device and the base station to which the first cell belongs isreleased.

When the terminal device determines that the RRC connection is notreleased, it indicates that the configuration of the first cell isabnormal, and therefore, when the timer expires (in other words, withinthe preset duration), an RRC connection release procedure is still notperformed between the terminal device and the base station to which thefirst cell belongs. In this case, no data is transmitted between theterminal device and the base station to which the first cell belongs.However, the RRC connection is still maintained between the terminaldevice and the base station to which the first cell belongs. To bespecific, the RRC connection is still maintained between a modem of theterminal device and the base station to which the first cell belongs,and therefore the modem of the terminal needs to continuously work. Thisincreases power consumption of the terminal device, and shortens abattery life of the terminal device. Therefore, the terminal deviceneeds to perform a cell handover, to avoid continuously camping on thefirst cell with the abnormal configuration and affecting the powerconsumption of the terminal device.

S206. The terminal device determines whether the terminal device iscurrently in a screen-off state. If the terminal device is currently ina screen-off state, S207 is performed; or if the terminal device is notcurrently in a screen-off state, S208 is performed.

S207. The terminal device hands over from the first cell to a secondcell, and records an identifier of the first cell.

Specifically, if the terminal device determines that the RRC connectionis not released, the terminal device is currently in a screen-off state,indicating that a user does not use the terminal device currently. Inthis case, if the terminal device performs a cell handover procedure,the user is not affected. Therefore, the terminal device may directlyhand over from the first cell with the abnormal configuration to thesecond cell. In this case, if the second cell is a cell with a normalconfiguration, after the terminal device hands over to the second cell,when no data is transmitted between the terminal device and a basestation to which the second cell belongs, an RRC connection may benormally released between the terminal device and the base station towhich the second cell belongs. This reduces the power consumption of theterminal device while ensuring user experience.

Further, when the terminal device moves to coverage areas of the firstcell and the second cell again, the terminal device may determine, byusing the recorded identifier of the first cell, that the configurationof the first cell is abnormal, to avoid accessing the first cell, andprevent the first cell with the abnormal configuration from affectingthe power consumption of the terminal device. This further reduces thepower consumption of the terminal device, and further prolongs thebattery life of the terminal device.

S205. The terminal device records an identifier of the first cell.

Specifically, if the terminal device determines that the RRC connectionis not released, the terminal device is currently in a screen-on state,indicating that the user currently still uses the terminal device. Inthis case, if the terminal device performs the cell handover procedure,unstable network experience is brought to the user. Therefore, when theterminal device is currently in a screen-on state, the terminal devicemay first record the identifier of the first cell with the abnormalconfiguration.

S209. The terminal device determines whether the terminal device entersa screen-off state from a screen-on state. If the terminal device entersa screen-off state from a screen-on state, S210 is performed; or if theterminal device does not enter a screen-off state from a screen-onstate, S209 continues to be performed.

Specifically, the terminal device may detect a current status of aterminal device screen in real time or periodically, to determinewhether the terminal device enters a screen-off state from a screen-onstate. Optionally, the terminal device may further determine, based onwhether a sleep instruction input by the user is received, whether theterminal device enters a screen-off state from a screen-on state.

S210. The terminal device determines whether an identifier of a cell onwhich the terminal device currently camps is the recorded identifier ofthe first cell. If the identifier of the cell on which the terminaldevice currently camps is the recorded identifier of the first cell,S211 is performed; or if the identifier of the cell on which theterminal device currently camps is not the recorded identifier of thefirst cell, S201 is performed.

Specifically, after determining that the terminal device enters ascreen-off state from a screen-on state, the terminal device comparesthe identifier of the cell on which the terminal device currently campswith the recorded identifier of the first cell, to determine whether theidentifier of the cell on which the terminal device currently camps isthe recorded identifier of the first cell. If the identifier of the cellon which the terminal device currently camps is the recorded identifierof the first cell, it indicates that the terminal device still currentlycamps on the first cell with the abnormal configuration, and theterminal device may perform the cell handover procedure, namely, S211.If the identifier of the cell on which the terminal device currentlycamps is not the recorded identifier of the first cell, it indicatesthat the terminal device has moved to another cell, and the terminaldevice may perform the procedure again to determine whether aconfiguration of a current camping cell is abnormal. This prevents thecell on which the terminal device currently camps from increasing thepower consumption of the terminal device.

S211. The terminal device hands over from the first cell to a secondcell.

Specifically, after entering a screen-off state from a screen-on state,when determining that the cell on which the terminal device currentlycamps is still the first cell, the terminal device performs the cellhandover procedure to hand over from the first cell to the second cell.Because the terminal device is currently in a screen-off state, itindicates that the user does not use the terminal device currently.Therefore, the terminal device performs the cell handover procedure, andthe user is not affected. This reduces the power consumption of theterminal device while ensuring user experience.

FIG. 3 is a schematic diagram 1 of power consumption of a terminaldevice according to an embodiment of the present invention. FIG. 4 is aschematic diagram 2 of power consumption of a terminal device accordingto an embodiment of the present invention. As shown in FIG. 3, when nodata is transmitted between the terminal device and a base station towhich a first cell belongs, a quantity of electricity consumed formaintaining an RRC connection is approximately 150 to 160 milliamperesper hour. As shown in FIG. 4, after the terminal device hands over fromthe first cell with an abnormal configuration to a second cell with anormal configuration, after the RRC connection between the terminaldevice and a base station to which the second cell belongs is releasedwhen no data is transmitted, a quantity of consumed electricity isapproximately 5 to 10 milliamperes per hour. To be specific, accordingto the cell handover method provided in this embodiment of the presentinvention, when the cell on which the terminal device currently camps isabnormal, after the terminal device hands over to another cell with anormal configuration, power consumption can be controlled within 10milliamperes per hour, and power consumption of camping on the cell withthe abnormal configuration is reduced by at least 100 milliamperes perhour, significantly reducing the power consumption.

According to the cell handover method provided in this embodiment of thepresent invention, when no data service is transmitted within presetduration, the terminal device that camps on the first cell may determinewhether the RRC connection to the base station to which the first cellbelongs is released. Further, when determining that the RRC connectionis not released, the terminal device may determine that theconfiguration of the first cell is abnormal, and hand over from thefirst cell with the abnormal configuration to the second cell. Thisavoids a problem that the power consumption of the terminal deviceincreases because the terminal device maintains the RRC connection tothe base station of the first cell, reduces the power consumption of theterminal device, and prolongs a battery life of the terminal device.

It should be noted that, the foregoing example describes the cellhandover method provided in this embodiment of the present invention byusing the first cell with the abnormal configuration as an example.However, a person skilled in the art may understand that the cellhandover method provided in this embodiment of the present invention isfurther applicable to the terminal device in the first cell with anormal configuration. When the terminal device has no data to transmit,the first cell with the normal configuration does not send an RRCconnection release request to the terminal, and consequently the powerconsumption of the terminal device increases, and the battery life ofthe terminal device is short. In addition, when no data is transmitted,the terminal device still maintains the RRC connection to the basestation to which the first cell belongs, and consequently networkresource utilization is relatively low. Therefore, in the methodprovided in this embodiment of the present invention, after the terminaldevice hands over to the second cell, the power consumption of theterminal device is reduced. In addition, the terminal device that handsover to the second cell releases a radio resource occupied by the RRCconnection to the base station to which the first cell belongs, so thatanother terminal device can use the radio resource, to improve networkresource utilization of the base station to which the first cellbelongs, and so on. For an implementation and an implementationprinciple, refer to the foregoing embodiment. Details are not describedherein again.

A person of ordinary skill in the art may understand that all or some ofthe steps of the method embodiments may be implemented by a programinstructing relevant hardware. The program may be stored in acomputer-readable storage medium. When the program runs, the steps ofthe method embodiments are performed. The foregoing storage mediumincludes any medium that can store program code, such as a ROM, a RAM, amagnetic disk, or an optical disc.

FIG. 5 is a schematic structural diagram of a terminal device accordingto an embodiment of the present invention. In this embodiment, theterminal device currently camps on a first cell, and the terminal deviceis further currently located in a coverage area of a second cell.Referring to FIG. 5, the terminal device may include a determiningmodule 11 and a handover module 12.

The determining module 11 is configured to: when determining that nodata service is transmitted within preset duration, determine whether aradio resource control RRC connection is released.

The handover module 12 is configured to: when it is determined that theRRC connection is not released, hand over the terminal device from thefirst cell to the second cell.

The terminal device may be configured to perform the foregoing methodembodiment. A specific implementation and a technical effect of thisembodiment are similar to those of the method embodiment, and detailsare not described herein again.

FIG. 6 is a schematic structural diagram of another terminal deviceaccording to an embodiment of the present invention. As shown in FIG. 6,in an implementation of this embodiment of the present invention, thehandover module of the terminal device may include:

-   -   a first determining unit 121, configured to determine whether e        terminal device is currently in a screen-off state and    -   a first handover unit 122, specifically configured to: when the        terminal device is currently in a screen-off state, hand over        the terminal device from the first cell to the second cell.        Optionally, the first handover unit 122 may be specifically        configured to: hand over the terminal device from the first cell        to the second cell, and record an identifier of the first cell.

The terminal device may be configured to perform the foregoing methodembodiment. A specific implementation and a technical effect of thisembodiment are similar to those of the method embodiment, and detailsare not described herein again.

FIG. 7 is a schematic structural diagram of still another terminaldevice according to an embodiment of the present invention. As shown inFIG. 7, in an implementation of this embodiment of the presentinvention, the handover module of the terminal device may include:

-   -   a second determining unit 123, configured to determine whether        the terminal device is currently in a screen-off state;    -   a recording unit 124, configured to: when the terminal device is        currently in a screen-on state, record an identifier of the        first cell;    -   a third determining unit 125, configured to: when the terminal        device enters a screen-off state from a screen-on state,        determine whether an identifier of a cell on which the terminal        device currently camps is the recorded identifier of the first        cell; and    -   a second handover unit 126, configured to: when the identifier        of the cell on which the terminal device currently camps is the        recorded identifier of the first cell, hand over the terminal        device from the first cell to the second cell.

The terminal device may be configured to perform the foregoing methodembodiment. A specific implementation and a technical effect of thisembodiment are similar to those of the method embodiment, and detailsare not described herein again.

FIG. 8 is a schematic structural diagram of still another terminaldevice according to an embodiment of the present invention. As shown inFIG. 8, the terminal device includes a processor 31 and a memory 34.Optionally, the terminal device may further include a transmitter 32, areceiver 33, and an antenna 35.

The memory 34, the transmitter 32, the receiver 33, and the processor 31may be connected by using a bus. Certainly, in actual application, thememory 34, the transmitter 32, the receiver 33, and the processor 31 maynot be of a bus structure, but may be of another structure such as astar-shaped structure. This is not specifically limited in thisapplication.

Optionally, the processor 31 may be specifically a general centralprocessing unit or an ASIC, may be one or more integrated circuits forcontrolling program execution, may be a hardware circuit that isdeveloped by using an FPGA, or may be a baseband processor.

Optionally, the processor 31 may include at least one processing core.

Optionally, the memory 34 may include one or more of a ROM, a RAM, and amagnetic disk memory. The memory 34 is configured to store data and/oran instruction that are/is required when the processor 31 runs. Theremay be one or more memories 34.

The processor 31 is configured to execute the instruction in the memory34, and when the processor 31 executes the instruction stored in thememory 34, the processor 31 performs the cell handover method performedby the terminal device. Details are as follows:

The processor 31 is configured to: when determining that no data serviceis transmitted within preset duration, determine whether a radioresource control RRC connection is released; and when determining thatthe RRC connection is not released, hand over the terminal device fromthe first cell to the second cell.

Optionally, in an implementation of this embodiment of the presentinvention, the processor 31 may be configured to: determine whether theterminal device is currently in a screen-off state; and when theterminal device is currently in a screen-off state, hand over theterminal device from the first cell to the second cell. Further, theprocessor 31 may be configured to: hand over the terminal device fromthe first cell to the second cell, and record an identifier of the firstcell.

Optionally, in an implementation of this embodiment of the presentinvention, the processor 31 may be configured to: determine whether theterminal device is currently in a screen-off state; when the terminaldevice is currently in a screen-on state, record an identifier of thefirst cell; when the terminal device enters a screen-off state from ascreen-on state, determine whether an identifier of a cell on which theterminal device currently camps is the recorded identifier of the firstcell; and when the identifier of the cell on which the terminal devicecurrently camps is the recorded identifier of the first cell, hand overthe terminal device from the first cell to the second cell.

The terminal device may be configured to perform the foregoing methodembodiment. A specific implementation and a technical effect of thisembodiment are similar to those of the method embodiment, and detailsare not described herein again.

As described in the foregoing embodiments, the terminal device in theembodiments of the present invention may be a wireless terminal such asa mobile phone or a tablet computer. Therefore, an example in which theterminal device is the mobile phone is used. FIG. 9 is a block diagramof a partial structure when a terminal device is a mobile phoneaccording to an embodiment of the present invention. Referring to FIG.9, the mobile phone may include components such as a radio frequency(Radio Frequency, RF) circuit 1110, a memory 1120, an input unit 1130, adisplay unit 1140, a sensor 1150, an audio frequency circuit 1160, aWireless Fidelity (wireless fidelity, Wi-Fi) module 1170, a processor1180, and a power supply 1190. A person skilled in the art mayunderstand that the structure of the mobile phone shown in FIG. 9 doesnot constitute a limitation on the mobile phone, and the mobile phonemay include more or fewer components than those shown in the figure, orcombine sonic components, or have different component arrangements.

The following describes each component of the mobile phone in detailwith reference to FIG. 9.

The RF circuit 1110 may be configured to: receive and send a signal inan information receiving or sending process or in a call process;particularly, after receiving downlink information of a base station,send the downlink information to the processor 1180 for processing; andsend uplink data to the base station. Generally, the RF circuit includesbut is not limited to an antenna, at least one amplifier, a transceiver,a coupler, a low noise amplifier (Low Noise Amplifier, LNA), a duplexer,and the like. In addition, the RF circuit 1110 may further communicatewith a network and another device through wireless communication. Thewireless communication may use any communications standard or protocol,including but not limited to Global System for Mobile Communications(Global System for Mobile communications, GSM), a general packet radioservice (General Packet Radio Service, GPRS), Code Division MultipleAccess (Code Division Multiple Access, CDMA), Wideband Code DivisionMultiple Access (Wideband. Code Division Multiple Access, WCDMA), LongTerm Evolution (Long Term Evolution, LTE), an e-mail, a short messageservice (Short Message Service, SMS), and the like.

The memory 1120 may be configured to store a software program and amodule. The processor 1180 executes various functional applications ofthe mobile phone and data processing by running the software program andthe module stored in the memory 1120. The memory 1120 may mainly includea program storage area and a data storage area. The program storage areamay store an operating system, an application program required by atleast one function (such as a sound play function or an image playfunction), and the like. The data storage area may store data (such asaudio data or an address book) created based on use of the mobile phone,and the like. In addition, the memory 1120 may include a high-speedrandom access memory, and may further include a non-volatile memory suchas at least one magnetic disk storage device, a flash memory device, oranother volatile solid-state storage device.

The input unit 1130 may be configured to: receive entered digit orcharacter information, and generate key signal input related to usersetting and function control of the mobile phone. Specifically, theinput unit 1130 may include a touch panel 1131 and another input device1132. The touch panel 1131, also referred to as a touchscreen, maycollect a touch operation performed by a user on or near the touch panel(for example, an operation performed by the user on or near the touchpanel 1131 by using any suitable object or accessory such as a finger ora stylus), and drive a corresponding connection apparatus based on apreset program. Optionally, the touch panel 1131 may include two parts:a touch detection apparatus and a touch controller. The touch detectionapparatus detects a touch position of the user, detects a signal broughtby the touch operation, and transmits the signal to the touchcontroller. The touch controller receives touch information from thetouch detection apparatus, converts the touch information into touchpoint coordinates, and sends the touch point coordinates to theprocessor 1180, and can receive and execute a command sent by theprocessor 1180. In addition, the touch panel 1131 may be implemented byusing a plurality of types such as a resistive type, a capacitive type,an infrared ray, and a surface acoustic wave. In addition to the touchpanel 1131, the input unit 1130 may include the another input device1132. Specifically, the another input device 1132 may include but is notlimited to one or more of a physical keyboard, a function key (such as avolume control key or an on/off key), a trackball, a mouse, a joystick,and the like.

The display unit 1140 may be configured to display information enteredby the user or information provided for the user, and various menus ofthe mobile phone. The display unit 1140 may include a display panel1141. Optionally, the display panel 1141 may be configured in a form ofa liquid crystal display (Liquid Crystal Display, LCD), an organiclight-emitting diode (Organic Light-Emitting Diode, OLED), or the like.Further, the touch panel 1131 may cover the display panel 1141. Whendetecting the touch operation on or near the touch panel 1131, the touchpanel 1131 transmits the touch operation to the processor 1180 todetermine a type of a touch event, and then the processor 1180 providescorresponding visual output on the display panel 1141 based on the typeof the touch event. In FIG. 9, the touch panel 1131 and the displaypanel 1141 are used as two independent components to implement input andinput functions of the mobile phone. However, in some embodiments, thetouch panel 1131 and the display panel 1141 may be integrated toimplement the input and output functions of the mobile phone.

The mobile phone may further include at least one type of sensor 1150,such as an optical sensor, a motion sensor, or another sensor,Specifically, the optical sensor may include an ambient optical sensorand a proximity sensor. The ambient optical sensor may adjust luminanceof the display panel 1141 based on brightness of ambient light, and theoptical sensor may turn off the display panel 1141 and/or backlight whenthe mobile phone approaches an ear. As one type of the motion sensor, anacceleration sensor may detect acceleration magnitudes in all directions(generally three axes), may detect a magnitude and a direction ofgravity when the acceleration sensor is stationary, and may beconfigured to recognize a posture application of the mobile phone (forexample, screen switching between landscape and portrait modes, arelated game, or magnetometer posture calibration), a vibrationrecognition related function (such as a pedometer or a knock), and thelike. For other sensors such as a gyroscope, a barometer, a hygrometer,a thermometer, and an infrared sensor that may be further disposed onthe mobile phone, details are not described herein.

The audio frequency circuit 1160, a speaker 1161, and a microphone 1162may provide an audio interface between the user and the mobile phone.The audio frequency circuit 1160 may receive audio data, convert theaudio data into an electrical signal, and transmit the electrical signalto the loudspeaker 1161, and the loudspeaker 1161 converts theelectrical signal into a sound signal for output. In addition, themicrophone 1162 converts a collected sound signal into an electricalsignal. The audio frequency circuit 1160 receives and converts theelectrical signal into audio data, and then outputs the audio data tothe processor 1180 for processing. The processor 1180 sends the audiodata to, for example, another mobile phone by using the RF circuit 1110,or outputs the audio data to the memory 1120 for further processing.

Wi-Fi is a short-distance wireless transmission technology. The mobilephone may help, by using the module 1170, the user receive and send anemail, browse a web page, access streaming media, and the like. TheWi-Fi module 1170 provides wireless broadband Internet access for theuser. Although the Wi-Fi module 1170 is shown in FIG. 9, it may beunderstood that the Wi-Fi module 1170 is not a mandatory component ofthe mobile phone, and may be omitted as required without changing theessence of the present invention.

The processor 1180 is a control center of the mobile phone, uses variousinterfaces and lines to connect all parts of the entire mobile phone,and performs various functions of the mobile phone and data processingby running or executing the software program and/or the module stored inthe memory 1120 and invoking data stored in the memory 1120, to performoverall monitoring on the mobile phone. Optionally, the processor 1180may include one or more processing units. For example, an applicationprocessor and a modem processor may be integrated into the processor1180. The application processor mainly processes an operating system, auser interface, an application program, or the like, and the modemprocessor mainly processes wireless communication. It may be understoodthat the modem processor may be not integrated into the processor 1180.

The mobile phone further includes the power supply 1190 (such as abattery) that supplies power to each component. Optionally, the powersupply may be logically connected to the processor 1180 by using a powermanagement system, to implement functions such as charging anddischarging management and power consumption management by using thepower management system.

The mobile phone may further include a camera 1200. The camera may be afront-facing camera or a rear-facing camera. Although not shown, themobile phone may further include a Bluetooth module, a GPS module, andthe like, and details are not described herein.

In this embodiment of the present invention, the processor 1180 includedin the mobile phone may be configured to perform the foregoing cellhandover method. Details are as follows:

When the mobile phone is currently in a first cell, and the mobile phoneis further currently located in a coverage area of a second cell, whendetermining, by using the modem processor, that no data service istransmitted within preset duration, the processor 1180 included in themobile phone may determine, by using the modem processor, whether an RRCconnection is released. In specific implementation, the processor 1180may determine, based on whether the modem processor receives a datapacket within the preset duration sent by using the RF circuit 1110, orwhether the modem processor sends a data packet by using the RF circuit1110 within the preset duration, whether no data service is transmittedwithin the preset duration. The processor 1180 may determine, based onwhether the modem processor receives, within the preset duration, an RRCconnection release request sent by a base station to which the firstcell belongs, whether the RRC connection is released.

When determining that the RRC connection is not released, the processor1180 included in the mobile phone performs, by using the RF circuit1110, an operation of handing over the mobile phone from the first cellto the second cell.

Optionally, in an implementation of this embodiment of the presentinvention, the processor 1180 included in the mobile phone maydetermine, by using the application processor, whether the mobile phoneis currently in a screen-off state, and when the mobile phone iscurrently in a screen-off state, perform, by using the RF circuit 1110,the operation of handing over the mobile phone from the first cell tothe second cell. In specific implementation, the processor 1180 maydetermine, based on whether the application processor receives a mobilephone screen-off event broadcast by the operating system of the mobilephone, whether the mobile phone is currently in a screen-off state.Further, the processor 1180 included in the mobile phone may beconfigured to: hand over the mobile phone from the first cell to thesecond cell, and record an identifier of the first cell.

Optionally, in an implementation of this embodiment of the presentinvention, the processor 1180 included in the mobile phone maydetermine, by using the application processor, whether the mobile phoneis currently in a screen-off state; when the mobile phone is currentlyin a screen-on state, record an identifier of the first cell; whendetermining, by using the application processor, that the mobile phoneenters a screen-off state from a screen-on state, determine whether anidentifier of a cell on which the mobile phone currently camps is therecorded identifier of the first cell; and when the identifier of thecell on which the mobile phone currently camps is the recordedidentifier of the first cell, perform, by using the RF circuit 1110, theoperation of handing over the mobile phone from the first cell to thesecond cell.

For a technical effect of the method embodiment performed by the mobilephone, refer to the foregoing embodiment. Details are not describedherein again.

1. A cell handover method comprising: camping, by a terminal device, ona first cell while being located within a coverage area of a secondcell; determining, by the terminal device, that no data service isreceived within a preset duration; determining, by the terminal device,whether a radio resource control (RRC) connection is released when nodata service is received within the preset duration; and handing over,by the terminal device, from the first cell to the second cell upondetermining that the RRC connection is not released.
 2. The methodaccording to claim 1, further comprising: determining, by the terminaldevice, that the terminal device is currently in a screen-off state,wherein handing over, by the terminal device, from the first cell to thesecond cell is initiated based on the determination that the terminaldevice is currently in the screen-off state.
 3. The method according toclaim 2, and further comprising recording an identifier of the firstcell upon handing over, by the terminal device from the first cell tothe second cell.
 4. The method according to claim 1, wherein the handingover, by the terminal device, from the first cell to the second cellcomprises: determining, by the terminal device, that the terminal deviceis currently in a screen-on state; recording, by the terminal device, anidentifier of the first cell based on the determination that theterminal device is currently in the screen-on state; determining, by theterminal device, that an identifier of a cell on which the terminaldevice currently camps is the identifier of the first cell when theterminal device enters a screen-off state from the screen-on state; andinitiating, by the terminal device, the hand over from the first cell tothe second cell based on the determination that the identifier of thecell on which the terminal device currently camps is the identifier ofthe first cell.
 5. The method according to claim 1, wherein the firstcell and the second cell are in an intra-radio access technology (RAT)communications network.
 6. The method according to claim 1, wherein thefirst cell and the second cell are in a plurality of inter-radio accesstechnology (RAT) communications networks.
 7. A terminal devicecomprising: a transmitter configured to camp on a first cell while beinglocated within a coverage area of a second cell; a receiver configuredto receive data service when camped on the first cell; a processorcoupled to the transmitter and the receiver, the processor configuredto: determine that no data service is received within a preset duration;determine whether a radio resource control (RRC) connection is releasedwhen no data service is received within the preset duration; and handover the terminal device from the first cell to the second cell via thetransmitter and receiver upon determining that the RRC connection is notreleased.
 8. The terminal device according to claim 7, wherein theprocessor is further configured to determine that the terminal device iscurrently in a screen-off state, wherein the hand over the terminaldevice from the first cell to the second cell is initiated based on thedetermination that the terminal device is currently in the screen-offstate.
 9. The terminal device according to claim 8, wherein theprocessor is further configured to record an identifier of the firstcell upon hand over of the terminal device from the first cell to thesecond cell.
 10. The terminal device according to claim 7, wherein theprocessor is further configured to: determine that the terminal deviceis currently in a screen-on state; record an identifier of the firstcell based on the determination that the terminal device is currently ina screen-on state; determine that an identifier of a cell on which theterminal device currently camps is the identifier of the first cell whenthe terminal device enters a screen-off state from the screen-on state;and initiate the hand over of the terminal device from the first cell tothe second cell based on the determination that the identifier of thecell on which the terminal device currently camps is the identifier ofthe first cell.
 11. The terminal device according to claim 7, whereinthe first cell and the second cell are in an intra-radio accesstechnology (RAT) communications network.
 12. The terminal deviceaccording to claim 7, wherein the first cell and the second cell are ina plurality of in an inter-radio access technology (RAT) communicationsnetworks.
 13. A non-transitory computer readable medium comprising acomputer program product for use by a terminal device, the computerprogram product comprising computer executable instructions stored onthe non-transitory computer readable medium such that when executed by aprocessor cause the terminal device to: camp on a first cell while beinglocated within a coverage area of a second cell; determine that no dataservice is received within a preset duration; determine whether a radioresource control (RRC) connection is released when no data service isreceived within the preset duration; and hand over from the first cellto the second cell upon determining that the RRC connection is notreleased.
 14. The non-transitory computer readable medium of claim 13,wherein the instructions, when executed by the processor, further causethe terminal device to determine that the terminal device is currentlyin a screen-off state, wherein the hand over from the first cell to thesecond cell is initiated based on the determination that the terminaldevice is currently in the screen-off state.
 15. The non-transitorycomputer readable medium of claim 13, wherein the instructions, whenexecuted by the processor, further cause the terminal device to recordan identifier of the first cell upon performing the hand over from thefirst cell to the second cell.
 16. The non-transitory computer readablemedium of claim 13, wherein the instructions, when executed by theprocessor, further cause the terminal device to: determine that theterminal device is currently in a screen-on state; record an identifierof the first cell based on the determination that the terminal device iscurrently in the screen-on state; determine that an identifier of a cellon which the terminal device currently camps is the identifier of thefirst cell when the terminal device enters a screen-off state from thescreen-on state; and initiate the hand over from the first cell to thesecond cell based on the determination that the identifier of the cellon which the terminal device currently camps is the identifier of thefirst cell.
 17. The non-transitory computer readable medium of claim 13,wherein the first cell and the second cell are in an in an intra-radioaccess technology (RAT) communications network.
 18. The non-transitorycomputer readable medium of claim 13, wherein the first cell and thesecond cell are in a plurality of in an inter-radio access technology(RAT) communications networks.
 19. The method according to claim 1,wherein the method is initiated when power consumption of the terminaldevice increases because a configuration of the first cell on which theterminal device camps is abnormal.
 20. The method according to claim 19,wherein the configuration of the first cell is abnormal when a parameterrelated to RRC disconnection to prevents a RRC connection releaserequest from being received by the terminal device when the terminaldevice is not in use.